In a scroll compressor, a fixed scroll and an orbiting scroll having spiral scroll wraps erecting perpendicularly on an end plate are engaged with each other with the scroll wraps, and thereby a refrigerant compressing section forming a compression chamber (closed operation chamber) therein is provided.
In the refrigerant compressing section, by rotating the orbiting scroll by a rotational driving shaft provided with a crankshaft, the crescent-shaped compression chamber formed by the scroll wraps is moved from the outside to the inside while the volume thereof is decreased. Thereby, a low-pressure refrigerant introduced to the inside is compressed into a high-pressure refrigerant.
Generally, in the scroll compressor of this type, lubricating oil is supplied to sliding portions and bearing portions to prevent the orbiting scroll from seizing. As the normal oil supply method, in the case of a vertical closed shell, journal bearings and thrust sliding portions on the back surface of the end plate of orbiting scroll are lubricated during or after the time when lubricating oil stored at the bottom of the closed shell is sucked up to the back surface of the end plate of orbiting scroll through a supply tube provided in the rotational driving shaft.
Also, some of the lubricating oil is sometimes supplied into the compression chamber to reduce gas leakage. One example thereof has been disclosed, for example, in Patent Document 1 (Japanese Patent Application Publication No. 2003-21085). In this Patent Document 1, lubricating oil is fed into a suction space of compression chamber via a lubricating oil supply tube incorporating a throttle pin as a throttling mechanism, and thereby the lubricating oil forms a thin film in the combustion chamber to reduce gas leakage by means of the sealing effect thereof.
However, the scroll compressor having the aforementioned lubricating oil supply mechanism has problems described below. In the scroll compressor described in Patent Document 1, the throttle pin for regulating the inflow quantity of lubricating oil is fixed to the fixed scroll, so that the position of a vertical hole for oil supply engaging with the fixed scroll must be designed with high accuracy, which increases the manufacturing cost.
Also, when accuracy necessary for positioning is required, a clearance between the vertical hole and the throttle pin becomes small, which poses a problem in that an adequate quantity of lubricating oil cannot be obtained. Further, as another example, a throttling mechanism using a nozzle has been disclosed, for example, in Patent Document 2 (Japanese Patent Application Publication No. 2002-81389). When a nozzle is used, however, there arises a problem in that the hole is clogged with dirt and wear particles. If the hole diameter of the nozzle is increased to prevent the clogging, lubricating oil is supplied any more than is necessary. In this case, the refrigerant dissolved in the lubricating oil performs the inherent job, so that the quantity of refrigerant discharged to the refrigerating cycle decreases, which poses a problem of decreased capability.